Shortenings can be composed of a mixture of a hard fat fraction and a soft fat fraction, with or without selected emulsifiers. The hard fat fraction is typically composed of, but not limited to, fully and/or partially hydrogenated canola, cottonseed, palm, or soybean oil, or a combination of such oils. The soft fat fraction typically comprises unhydrogenated oils or partially hydrogenated oils, or any combination thereof. The relative proportions of the hard fat fraction and the soft fat fraction will play a role in determining the properties of the shortening product.
It has been suggested in the literature that the consumption of trans fatty acids and saturated fatty acids can increase the amount of LDL cholesterol in the body, and that consumption of trans fatty acids also can reduce HDL cholesterol levels. Therefore, it may be desirable to reduce both saturated fats content and trans fats content in certain prepared food products. The removal of trans fats from a shortening product can pose difficulties for the food producer. Trans fat free products tend to have a lower viscosity or a softer solid nature and a lower melting point than those containing trans fat. If the melting point of the fat is too low, the product may run, bleed, or melt at typical handling temperatures.
Hydrogenation was initially introduced into shortening manufacture in an effort to provide the shortening with more desirable physical properties, particularly hardness, at a variety of handling temperatures. Complete hydrogenation increases the level of saturated fatty acids. Partial hydrogenation will provide lower levels of saturated fats than complete hydrogenation, but can increase the level of trans fatty acids.
U.S. Pat. No. 5,470,598 discloses a β-prime stable plastic shortening stated to exhibit superior baking and frying performance and containing reduced levels of saturates and trans fatty acids. The shortening is stated to be useful in confectionery, baking, and frying applications. The disclosed shortening comprises from about 6% to about 25% by volume of an inert gas and from about 75% to about 94% by volume of a fat phase comprising: a) from about 74% to about 90% by weight of a base oil having less than 10% by weight of trans fatty acids, less than 16% C4-C26 fatty acids, b) from about 10% to about 20% by weight of a β-prime stable crystalline hardstock consisting essentially of at least 65% of PSP and PSS, wherein the ratio of PSP:PSS is at least 0.8 to 1.0 and from 0 to 30% other triglycerides or synthetic fats and from 0 to 5% monoglycerides or diglycerides.
U.S. Pat. No. 7,169,430, assigned to the present assignee herein and incorporated herein by reference in its entirety, discloses shortening systems which are prepared to include hydrogenated edible oils that are hydrogenated in a manner to minimize the formation of trans-stereoisomers. A conditioned catalyst is used which disfavors trans-stereoisomer formation without significantly negatively impacting the length of time required to form solids for a useful shortening base stock through hydrogenation. In one embodiment, the conditioning agents are organic acid phosphates and phosphoric acid. In another embodiment, a confectionary shortening is provided which incorporates a polyglycerol ester emulsifier.
Other research on the topic of shortening products is disclosed in “A comparison of lipid shortening functionality as a function of molecular ensemble and shear: Crystallization and Melting”, Humphrey, K. L., Narine, S. S., Food Research International 37 (2004) 11-27; “A comparison of lipid shortening functionality as a function of molecular ensemble and shear: microstructure, polymorphism, solid fat content and texture”, Humphrey, K. L., Narine, S. S., Food Research International 37 (2004) 28-38; and “Extending the capability of pulsed NMR instruments to measure solid fat content as a function of both time and temperature,” Narine, S. S. and Humphrey, K. L., JAOCS 81, 101-102 (January 2004); each of which is incorporated herein by reference in their entireties.
There is a need for shortenings having reduced levels of saturated fats and trans fats, and acceptable physical properties for handling and food preparation.